1. Field of the Invention
The invention relates to locking devices; and more particularly to slide bolt type locks which provide a rigid bar connection between the door and jamb.
2. Description of the Prior Art
Slide bolts are one of the earliest forms of locking means. They have taken the form of rigid members which can be either rotated or slid from a position on the member to be secured into a keeper on a rigid adjacent surface such as a door jamb. It has long been recognized that doors and windows may occasionally be advantageously held ajar or may be opened for a brief period of time while still retaining the security of a link between the door and jamb. The most common means of cheaply providing this limited opening function, is the well known chain which is mounted upon a door frame and connectable via a slide channel to the door itself. The art also includes other members in connection with window and door control whereby the member is mounted for example upon the frame and projects outwardly therefrom. In some instances a keeper upon the door or window is tracked by the projecting element and means are provided for securing these elements together at any predetermined position.
It is observed that the most important element in any security device, is the degree of reliability provided. This feature is importantly related to the mounting ease and operating ease of the unit when one considers the large number of non-professional installations involved. A general feature that has heretofore been lacking in devices of this type, relates to the ability to engage them from the opposite side of the door. Typically, one member of a family may be at home while the other is out. The security afforded by this type of device will prompt the occupant to use it. On the other hand, if the absent party is not able to gain access it requires disturbance of the occupant and often considerable inconvenience.
As the typical example of slide bolt and chains demonstrate, the prior art has also failed to provide a suitable dual purpose unit that can be employed for either rigid internal slide bolt protection or limited opening of the door or window.